Ladder inclinometer



Dec. 8, 1964 G. LIEBLEIN 3,159,924

LADDER INCLINOMETER Filed Nov. 20. 1961 INVENTOR.

George Leblen ATTORNEYS United States Patent O 3,159,924 LADDER HJCLWGWTER George Liebiein, P). Box 297, Amityville, NX. Filed Nov. 20, 196i, Ser. No. 153,3?2 4 Claims. (Cl. 313-207) The present invention relates to inclinometers, and is more particularly concerned with a structure adapted to be removably mounted on a ladder and useful in adjusting such a ladder to a particular angle relative to vertical.

As is well known, ladders of Athe extension or other types are normally positioned at an angle to and against a vertical structure, thereby to derive their support and to support a person thereon. The actual angle at which such a ladder is placed against a vertical structure, e.g. a wall, or the like, often depends upon the desires and personal preferences of one using the ladder in any given situation; but a far more common circumstance is for a ladder toy be angularly propped against a supporting structure without any regard for or special consideration being given to the angle at which the ladder is so disposed.

In practice, it has been found that many ladder accidents result from and can be directly attributed to an improper angular disposition of the ladder. 1f the ladder is too steep, i.e. describes too small an angle between itself and the supporting structure, the resulting ladder configuration tends to pivot in a backward direction, thereby falling away from the supporting structure and on top of one using the ladder. In this too-steep situation, moreover, the possibility of accidents is aggravated due to the fact that, by reason of the steepness of the ladder structure, a person on the ladder tends to feel unsafe and may, in an effort to derive a greater feeling of security, forceably grasp the ladder side rails or rungs, thereby causing the ladder to fall to one or another side, or facilitating its backward shift.

Accidents also commonly occur when the ladder is not steep enough, i.e. describes too wide an angle between itself and the supporting structure. In such circumstances, it is common for the feet of the ladder to suddenly slide in a rearward direction, dropping a person on the ladder to the ground.

These circumstances surrounding unsafe ladder angles have been long recognized. In an effort to achieve a best compromise between too steep and too shallow a ladder angle, many safety organizations have, over the years, recommended that the ladder be positioned to describe an angle of l5 degrees between itself and a vertical supporting structure. This angle of degrees has, moreover, been adopted as the recommendation of organizations extensively using ladders, e.g. public utilities, etc.; and most source materials which go so far as to suggest an angle, ordinarily suggest that the angle be l5 degrees. Notwithstanding this situation, persons using ladders may still be subject to the perils described previously since, without special measuring instruments, it is difficult to place a ladder at an angle of l5 degrees; and if such measuring instruments are dispensed with, an approximate positioning of the ladder by eye or the like may Well resuit in one of the more dangerous conditions described previously.

In an effort to obviate the aforementioned diiculties, it has been suggested heretofore that ladders may have some form of inclinometer structure incorporated into a side rail thereof as an integral or unitary part of the ladder. This suggestion, while going somewhat toward solving the problems described previously, has raised the additional problems of expense, etc., attendant the ladder, thereby militating against widespread adoption of this structure; and has further been subject to the disadvantage that the only ladders which are thereby safely positioned are those which incorporate the inclinometer struc- Patented Dec. 8, 1%64 ice ture as an integral part thereof. These problems of expense and permanent attachment of the inclinometer have, in practice, effectively defeated the very purposes of the structure; for, by reason of said problems, inclinometer structures of types suggested heretofore have found little favor, whereby the safety hazards mentioned have continued to exist on a large scale.

The present invention, recognizing this existing situation, is therefore concerned with the provision of a ladder inclinometer which is far less expensive to manufacture and supply than other inclinometers suggested heretofore, whereby it may achieve much more widespread usage than has been the case in the past.

A still further object of the present invention resides in the provision of a ladder inclinometer so arranged that it may be readily mounted upon and removed from a ladder structure, whereby a given inclinometer structure can position a plurality of ladders to their safest angle without requiring that the ladders themselves be of any special construction.

Still another object of the present invention resides in the provision of an improved ladder inclinometer adapted to permit a ladder user to quickly position the angle of his ladder to thatY angle presently recommended as safest by national safety organizations, public utilities, and the like.

Still another object of the present invention resides in the provision of a ladder inclinometer of the bubble level type, having a novel and highly improved mounting structure adapted to permit said inclinometer to be Vused with various different ladders.

In providing for the foregoing objects and advantages, the present invention contemplates the provision of an inclinometer generally of the bubble type, having a spirit level mounted in a supporting member which is in turn associated with supporting plates adapted to frictionally and/ or resiliently engage the side rails of a ladder. The said supporting plates preferably engage opposed linear edges of a ladder side rail; and Ythe said supporting plates are, moreover, so positioned with respect to the aforementioned spirit level that, when the supporting plates do properly engage the ladder side rail edges, the spirit level will indicate a level condition when the ladder side rail edges are inclined at 15 degrees to vertical. y

By the arrangement described, the inclinometer of the present invention may be readily placed on the side rail of an existing ladder, whereafter the ladder may be angularly positioned by merely watching the bubble in the spirit level; and the said inclinometer may thereafter be removed for safe keeping, or may be immediately used in conjunction with any other ladder which it is desired to position.

The foregoing objects, advantages, construction, and operation of the present invention will become more readily apparent from the following description and accompanying drawings, in which: Y

FIGURE 1 is a perspective View of a ladder having the inclinometer of the present invention mounted thereon.

' FIGURE 2 is a side view of my improved inclinometer, constructed in accordance with the present invention.

FlGURE 3 is a top view my improvedvinclinometer structure, taken on line 3-3 of FIGURE 2; and

FIGURE 4 is a partial cross-sectional view of the inclinometer structure, taken on line 4-4 of FIGURE 2.

Referring now to the several igures, like numerals of which refer to like parts throughout, it will b e seen that an inclinometer constructed in accordance with th'e pres"- ent invention may comprise a central supporting member 10 associated with a pair of supporting plates 11 and 12; The overall arrangement, as shown in FIGUREl, is such that the supporting plates 11 and 12 are adapted to grasp opposed velongated edges of a ladder side rail13,i-while member is adapted `to overlie an intervening portion of the side rail. In so grasping Vthe ladder side rails, the plates 11 and 12 are, moreover, intended to lie along the directions of elongation of each such edge for a significant distance thereby not only to position the inclinometer on the ladder at a precise angle relative to the ladder, but also to assure that Vthe inclinometer, as so positioned, accurately assumes the angular position of the ladder itself.

Central supporting member 10 is, as shown in the several drawings, ofrplana'r configuration; and said member 10 is, moreover, shaped as a parallelogram. The upper and lower edges of member 10 lare, when a ladder associated with the inclinometer is properly positioned, clis-` posed in a generally horizontal direction; and the angularly inclined sides of the parallelogram-shaped member 10 are -then disposed (as best illustrated in FIGURE 2) at the desired final angle of the ladder, i.e. in a preferred case, 15 degrees. As a result of this overall arrangement, therefore, it will be appreciated that the parallelogramshaped member 10 is, in effect, adapted to be removably superimposed upon a section of a ladder side rail and, when so superimposed, is adapted to accurately assume the same positionas the corresponding underlying section of the ladder side rail itself.

In order to achieve thisy positioning of the supporting section 10, the aforementioned side plates 11 and V12 are caused to extend outwardly from, and at the angle of,

' the angularly inclined edges of member 10. In a preferred arrangement, the supporting plates 11 and 12 Iare attached to the angular edges of member 10 at a substantially centrally located linear portion `ofeach said plate 11 and 12 whereby the overall configuration assumes, in

cross-section, a generally H-shape, as best shown in FIG- URE 3. By this arrangement, each of the plates 11 and 12 defines a pair of gripping portions extending outwardly from opposite sides of supporting member 10; and the overall mounting member thus provided by members 10 through 12 inclusive is adapted to engage either side rail of a ladder, and is :also adapted to engage either such side rail from either an inner or outer surface thereof. Y

Ordinarily the spacing in a horizontal direction between the supporting plates 11 and 12 .is selected to correspond to that generally provided in many commercial ladders presently being marketed, e.g. three inches is a common side rail width dimension. The provision of a corresponding horizontal spacing between the members 11 Iand 12 permits the inclinometer to be used directly on many ladders already in existence; and the inclinometer itself is supported by frictional engagement or by a press-fit arrangement which immediately occurs when the plates 11 and 12 are slid over the edges of the side rail 13, all as illustrated in FIGURE 1. In a preferred embodiment, the` supporting member 1 and its'associated plates 11 and 12, are formed as a unitary structure, e.g. of plastic and by a molding operation; and theremainder of the structure to be described may be simultaneously molded. When such a plastic material is employed, moreover, someV resilience is exhibited between the plates 11 and 12 and their associated central member 10; and this resilience permits the inclinometer of the present invention to be employed on ladders having side rails departing somewhat from a given standard width, or to be used on ladders having various width side rails within a preselected range of widths consistent with the resilience mentioned.

The lower portion of the member 10 is enlarged, as at best shown in FIGURE 4, to provide a bubble housing structure 16. In particular, structure 16 defines, adjacent its center, a cavity 16a in which is placed a sealed liquidcontaining glass vial 17 having a central area 17a associated with indicia lines, all.to provide a bubble level structure generally similar to those well known in the art. In forming the cavity 16a, the upper portion of member 1i) may, as is shown in FIGURES 3 and 4, be moldedgto define a side wall lob and a pair of spaced covering edge or lip portions 16C. With this arrangement, the cavity 16a underlies the lip portions 16e, as illustrated, thereby to permit the sealed vial 17 to be slipped into the side of cavity 16a under said portions 16C and toward side wall 16h (see FIGURE 4), after which the housing structure 16 can be completed by adhesively securing a cover side plate 16d in place. In short, the overall structure, including the recess 16a, is, except for side plate 16d, formed as a single molded part; and after vial 17 is slipped into place, under lips 16C, said vial is firmly held in place by the addition of side plate 16d.

To facilitate the aforementioned assembly of parts as wel] as the final positioning of vial 17, the upper portion 16 of the inclinometer structure may, in the region of cavity 16a, be formed with underlying and end supporting par-ts adapted to `closely conform to the shape and disposition of lthe glass Vial 17. Such -a unitary shaped supporting structure is particularly desirable when the glass vial 17 is of curved configuration, as illustrated. It" should, moreover, be noted thatrupper portion 16 of supporting plate 10 acts not only to hold glass vial 17 in place, but also acts to reinforce the inclinometer structure at its upper portion, much in the same way that ribs 14 and 1,5 reinforce the structureV at is lower end. Again, in order to avoid heavy sections, the extremities of upper reinforcement portion 16 can be hollowed out, as at 18 and 19; but such structure is optional.-

In the arrangement shown, and by reason of the interrelation of the various parts described, the bubble in vial 17 assumes a central position between its associated indicia lines only when the upper and lower edges of parallelogram-shaped supporting member 10 are disposed horizontally; and it will be appreciated that this horizontal disposition of said upper and lower edges of member 10 can occur only when its angular side edges are inclined at a desired 15 degrees to vertical. This consideration in turn requires that plates 11 and 12 be themselves inclined at l5 degrees to vertical; and by reason of the fact that the plates 11 and lf2 are, when mounted on a ladder, intentionally designed to conform to extended linear areas of the ladder side rail, the ladder side rail itself must be at 15 degrees to horizontal. In short, the arrangement is such that a level position will be shown by the bubble level of the inclinometer only when the ladder is inclined at the desired angle, e.g. 15 degrees. Y

It will be appreciated that while I have described a preferred embodiment of the` present invention, many variations may be made without departing from the spirit of the yappended claims. By way of example, in apreferred embodiment of the invention, the upper and lower edges of the plates 11 and 12 are coextensive with the uppermost and lowermost edges of the central member 1t).4 The heights of the plates 11 and 12 may, however, vary from that of central member 10. Moreover, while in a preferred arrangement the plates l11 and 12 are formed integral with central member 1G, this is not mandatory; and said members may beformed as separate pieces which are thereafterattached to the edges of member 16. Indeed, in so attaching the plate members 11 and 12, provision may be made for varying their positions relative to one another, thereby to facilitate the use of the inclinometer of the present invention on ladders having side rails of various different widths.

Finally, it will be appreciated that, while the bubble level of the present invention is, in a preferred embodiment of the invention, centrally mounted in an uppermost portion of supporting member 10, variations in the` Y rection of extension of said bubble Vial and the side supporting plates is maintained.

Other variations will be suggested to those skilled in the art, and it must therefore be emphasized that the foregoing description is meant to be illustrative only and should not be considered limitative of my invention. All such modications and variations as are in accord with the spirit of the invention are meant to fall within the scope of the appended claims.

Having thus described my invention, I claim:

1. An inclinometer for angularly positioning a ladder, comprising a supporting plate of generally parallelogram shape having upper and lower generally horizontal edges and a pair of angularly inclined interconnecting side edges,

said side edges being disposed in parallel relation to one another and at an angle to said upper and lower edges corresponding generally to a predetermined angle at which it is desired to position said ladder relative to horizontal, means defining an elongated cavity adjacent to and extending along one of said horizontal edges of said supporting plate, bubble level means carriedby said supporting plate within said cavity ladjacent and generally parallel to said one of said generally horizontal edges and adapted to indicate a desired level position when said upper and lower edges are horizontal and when said interconnecting side edges are thereby at said predetermined angle to horizontal, said cavity defining means including both vertically and horizontally extending structural members for holding said bubble level means in predetermined xed position relative to said upper, lower, and side edges of said supporting plate, and a pair of resiliently movable side plates aixed to said supporting plate along said pair of interconnecting side edges thereof respectively, the planes of the side plates being -angularly disposed to'said upper and lower supporting plate edges at the angle of said side edges, said side plates extending in generally parallel relation to one another and extending outwardly from said supporting plate adjacent both of the opposite faces of said supporting plate, said supporting plate and said side plates being joined to one another in a substantially H- shaped configuration, said pair of side plates thereby being adapted to resiliently grasp and to removably engage the elongated opposed edges of a ladder side rail on either side of said ladder.

2. The inclinometer of claim 1 'wherein said pair of side plates have upper and lower edges generally coextensive respectively with the upper and lower edges of said supporting plate.

3. The inclinometer of claim 1 wherein said supporting plate and said outwardly extending side plates are integral with one another, said supporting and side plates comprising a plastic material. Y

4. In an inclinometer adapted for use in angularly positioning a ladder, removable mounting means comprising a pair of resilient planar side plates formed of a plastic material and disposed in spaced substantially parallel relation to one another, the spacing between said plates being substantially equal to the width of a side rail of said ladder, a planar web of plastic material extending transverse to both of said side plates between facing central line areas of said plates, said side plates and said web bep ing formed as a unitary molded plastic structure whereby side therebetween, and an elongated spirit level mountedl on said web at a position between said side plates, the direction of elongation of said spirit level beting iixed at a predetermined acute angle to one of said side plates and at a predetermined obtuse angle, complementary to said acute angle, relative to the other of said side plates.

References Cited bythe Examiner UNITED STATES PATENTS i 1,200,410 10/16 Chemrinsky 334-207 1,256,909 9/ 18 Kroshaug 248-210 1,341,553 5/20 Hahne 33-207 2,386,833 10/45 Baldwin 33-207 2,845,719k 9/58 Y Thomifszer 33-207 2,895,700 7/59 Johnson 248-210 3,052,442 9/62 Rankin l. 248--210 ISAAC LISANN, Primary Examiner. 

1. AN INCLINOMETER FOR ANGULARLY POSITING A LADDER, COMPRISING A SUPPORTING PLATE OF GENERALLY PARALLELOGRAM SHAPE HAVING UPPER AND LOWER GENERALLY HORIZONTAL EDGES AND A PAIR OF ANGULARLY INCLINED INTERCONNECTING SIDE EDGES, SAID SIDE EDGES BEING DISPOSED IN PARALLEL RELATION TO ONE ANOTHER AND AT AN ANGLE TO SAID UPPER AND LOWER EDGES CORRESPONDING GENERALLY TO A PREDETERMINED ANGLE AT WHICH IT IS DESIRED TO POSITION SAID LADDER RELATIVE TO HORIZONTAL, MEANS DEFINING AN ELONGATED CAVITY ADJACENT TO AND EXTENDING ALONG ONE OF SAID HORIZONTAL EDGES OF SAID SUPPORTING PLATE, BUBBLE LEVEL MEANS CARRIED BY SAID SUPPORTING PLATE WITHIN SAID CAVITY ADJACENT AND GENERALLY PARALLEL TO SAID ONE OF SAID GENERALLY HORIZONTAL EDGES AND ADAPTED TO INDICATE A DESIRED LEVEL POSITION WHEN SAID UPPER AND LOWER EDGES ARE HORIZONTAL AND WHEN SAID INTERCONNECTING SIDE EDGES ARE THEREBY AT SAID PREDETERMINED ANGLE TO HORIZONTAL, SAID CAVITY DEFINING MEANS INCLUDING BOTH VERTICALLY AND HORIZONTALLY EXTENDING STRUCTURAL MEMBERS FOR HOLDING SAID BUBBLE LEVEL MEANS IN PREDETERMINED FIXED POSISUPPORTING PLATE, AND A PAIR OF RESILIENTLY MOVABLE SIDE 